Rotary conductor

ABSTRACT

An electrical coupling device providing a series of continuous, unbroken, unsliding electrical connections between two relatively rotatable members over a limited angular displacement. The coupler is provided with two coaxially related members that are rotatably interconnected for angular displacement, and between the members is provided in axially spaced array a series of isolated flexible electrical conductors that are coiled and uncoiled between the said members with rotative displacement between the members.

United States Patent Inventors George Wendell; 3,251,955 5/1966 Erickson191/12 Le Roy J. Knkkern; Walter F. OBrien, Jr., 3.430,l79 2/1969 Shoji339/5 pp No g Primary ExaminerRichard E. Moore If B. L d Al Filed Mar.1970 Attorneys A red evrne an an C Rose [45] Patented Aug. 10, 1971Assignee Litton Precision Products, Inc.

Blacksburg, Va.

14 Claims, 11 Drawing Figs.

g device providing a series of continuous, unbroken, unslidingelectrical connections between two relatively rotatable members over alimited an {54] ROTARY CONDUCTOR ABSTRACT: An electrical couplin lardisplacement. The coupler is provided with two coaxially related membersthat are rotatably interconnected for angular displacement, and betweenthe members is provided in axially spaced array a series of isolatedflexible electrical conductors that are coiled and uncoiled between thesaid members with rotative displacement between the members.

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PATENTED AUG 1 0 I97:

8HEU10F3 mvzamons F I6, I I GEORGE WENDELL LEROY J. KNISKERN WALTER FO'BR|EN,JR.

ATTORNEY PATENTEU AUG 1 0 I971 SHEU 2 OF 3 IN VEN TORS GEORGE WE N DE LLLEROY J. KNISKERN WALTER F. Q'BRIEN,JR. 4%! 5/ ATTORNEY PAIEmEumsmmSHEET 3 BF 3 v INVENTORS GEORGE WEN DELL LEROY J. KNISKERN WALTER F.O'BRIEN,JR

' ATTORNEY ROTARY coNuucroa FIELD OF INVENTION This invention relates toimprovements in-rotary electrical conductors and is more particularlydirected to multiplecircuit rotary electrical couplings for providing alarge number of continuous electrical connections over a limitedrotarydisplacement that may involve up to one or more revolutions.

BACKGROUND OF THE INVENTION limited rotation has also been provided inthepast by joining the members with leads or conductors that may twistor bend as the members are relatively rotated to provide continuous,unbroken connections between the parts. 7

SUMMARY OF THE INVENTION I The present invention provides amulticircuitrotary electrical coupler of the latter type providing a plurality ofunbroken circuit connections between two relatively rotatable membersover. limited angular displacement that may involve any fraction orvmultiple of a complete revolution. This coupler is provided in aminiature unit of very small size yet is capable of supplying acomparatively large number of separate circuit connections over arelatively large angle of rotation between the members, and requiringbut a very small torque for rotatable displacement. Additionally, thecoupler provides an improved manner of insulating the multipleelectrical circuits from each other, and protecting and isolating thecircuits from one another and from external movable parts to protect theconductors from breakage or injury. Additionally, the conductors arearranged in such manner as-to be' capable of a relatively large lifecycle of operation involving a comparatively large number of cycles ofoperation without breakage or fatigue.

DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view, partly insection, illustrating a multicircuit rotary coupler according to thepresent invention.

FIGS. 2, 3 and 4 are sectional views taken through the same crosssection of FIG. 1 and illustrating the coiling of the internalelectrical conductor for different angular displacements.

FIGS. 5 to 9, inclusive, are perspective views sequentially illustratingthe construction and assembly of a preferred multicircuit rotarycoupling according to the invention; and, v

. FIGS. and II are cross-sectional schematic illustrations of analternative embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS struction having aninner bearing race 18 on the inner drum 11, an outer bearing race 19 onthe inside of the outer tube 13, and ball bearings 17.

The inner drum-l1 is provided with a hollow extended por-- tion 12 forreceiving at the inlet a series of insulated electrical conductor wires50 that pass through the hollowcore of extension 12 and into the hollowinterior of drum 11.

2 The drum 11 is formed with a series of radially arrangedcircumferential slots l4, l5 and 16 disposed along its length and y witha different slot being provided corresponding to each different one ofthe inlet conductor leads 50. Each such slot accommodates a spirallywound flat strip of metal conductor Z0 that generally resembles aspirally wound spring, as best viewed in FIGS. 2, 3 and 4. The inner end25 of each such spiral conductor strip 20 is fastened: to the inner drumII and passes through a slot 24 (FIG. 2). provided in the drum 11 andleading to the interior of the drum. l-l. Inside of the drum 11, thisend 25 of each of thewire strips'20 is adapted to beelectricallyconnected to a different one of the inlet. conductor leads 50. I I v Theouter end 21 of each such spiral conductor strip 20 is fastened at theoutside of outer tube: 13 and passes through a slot formed. through thetube 13' to, provide a series of spaced electrical contacts 21 outsideof thecoupler as best shown in FlG.l.

In a preferred construction, there is provided an evennumber of spirallywound conductors 20 with alternate ones being wound in clockwise andcounterclockwise, directionsto balance out the spring torquesanditherefore minimize the turning torque. Other windings mayrbeemployed solong as the total number-of strips wound clockwise equalsthetotalnumber counterclockwise.

Thus, each one of the inlet electrical wire leads 50 passing. into theinterior of extension 12 ofthe drum 11 is connected to the insidecontact 25 of a different one of the spirally wound strips 20, andelectrical conduction is madethrough that spirally wound strip 20 to aseparate electrical contact'ZI connectedtto and accessible fromtheoutside of the'outer tube 13. t

From the above description, the modeof operation of this rotary couplerin providing continuous electrical connection for each lead duringrotation of thetmember II or II isbelieved evident as illustratediin FIG2, 3 and'4..,As shown, clockwise rotation-of the outer tube l3'abouttheinner drum 11 serves to progressively wind the-.coils'of each-one ofthe clockwise strip conductors 20 more-tightly together so thatfollowing one or more revolutions of: the outer tube 13;.the coils ofsuch conductors 20 progressively close together to a tightly woundposition as best shownin FIG. 4. Concurrently, those strips woundcounterclockwise are unwound. Since each strip coil 20 isaccommodatedwithinits own radial slotprovided in drum 11, each ofthese spiral stripconductors is very effectively insulated from the other: conductors anda comparatively large number of separaterotatable electrical connectionsmay be provided within a small miniaturized rotary coupler unit;

The spiral strip connectors 20 are preferably made of thin materialhaving a relatively low springconstant yet capable of cyclic operationsfor a sufficiently large number of 'rotative displacements as desiredwithoutexcessive fatigue and rupture; This permits theIun it to berotated with but a small drive,

torque-so'as to impose only a small load upon any rotary drive element.Furthermore. the alternateclockwise and counterclockwise windings of thestrips 20 reduces or'balances the torque.

It will be noted that eachcoil or spiral winding 20'is completelyenclosed inside of the rotary unit except for itsouter contact 21 andits inner contact 25. Each insidecoil is also completely protected andinsulated from the'others'inside' of the unit by the sidewalls ofits-slot formed in'th'e inner drum 11. This arrangement thereforeprovidesthe. desired compactness, insulation, and protection of theleads, strips and conductors from shock, acceleration andphysicalcontact with other moving parts as might be desired or required for manyindustrial applications.

FIGS. 5 to 9, inclusive, illustratea preferred multiple-conductorconstruction for providing a larger number of conductors in a smallvolume rotary device that is also comparatively inexpensive toconstruct.

In this embodiment, the coiled strip conductors are not individualconductors 20, as in FIGS. 1 to 3, above, but instead are provided inthe form of a flexible flat insulator tape 30 and 31, each supporting aseries of parallel-arranged thin electrical conductor strips 33, 34, 35and 36 that are embedded into or printed on the flexible insulator tape30 and 31.

As best shown in FIGS. 5 and 6, an even number of suchinsulator tapesare provided, each having the same number of conductors. One end of eachtape 30 or 31 is attached to a hollow drum 37, passing into a slot 39formed in the drum 37 leading to its interior. Electrical inlet wires 50(FIG. 5) passing into the interior of the drum 37 are each electricallyjoined to a different one of the strip conductors 33, 34, 35 and 36 toprovide continuous electrical contact from each inlet wire 50 to adifferent one of the strip conductors 33, etc.

For minimizing the turning torque, alternate ones of the flexibleinsulator tapes 30 and 31 are wound counterclockwise and clockwise, asshown in FIG. 6, so that rotation of the drum 37 in either directionserves to coil one tape 30 more tightly while uncoiling the other 31more loosely.

The flexible insulating tapes 30 and 31 perform the function ofsupporting the individual conductors and maintaining mechanical spacingand electrical insulation between the conductors.

After the opposite winding of the flexible circuit tapes 30 and 31 aboutthe inner drum 37 in FIG. 6, a hollow sleeve 40 (FIG. 7) is placed overthe wound tapes 30 and 31 and concentric about the inner drum 37. Outersleeve 40 is provided with an elongated slot 41 running lengthwise fromone end and leading to a forward projecting ring 42 about the sleeve 40adapted to receive output terminal wires.

As best shown in FIG. 8, the slotted sleeve 40 completely encloses thespirally wound circuit tapes 30 and 31 except for the outer ends of theconductor carrying tapes that are passed through the slot 41 forelectrical connection. The stripped ends 44 of electrical wireconductors 45 are electrically connected to each one of the stripconductors 33, 34, etc. and the insulated portions of such wires 45 arepassed through the openings 43 in the forward ring 42 to provide anoutlet electrical connection to each of the conductors 34, 35, etc. ofthe flexible tapes.

To complete the construction shown in FIG. 9, an unslotted outer hollowsleeve 47 is placed coaxially over the slotted sleeve 40, and having oneend near the end flange 38 on the inner drum 37 and the other endthereof extending to and fastened upon the ring 42 that supports theoutlet conductors 45. Although not shown, suitable bearings are providedbetween the inner drum 37 and the slotted sleeve 40 to permit relativerotation between these members. The outer sleeve completely encloses thetapes and wire connections.

Operation of the rotary coupler of FIGS. 5 to 9 is similar to that ofFIGS. 1 to 4 previously described in that relative rotation between theinner drum 37 and sleeve 40 (and connected sleeve 47) serves to coil anduncoil the circuit-carrying flexible tapes 30 and 31 thereby providingmulticircuit continuous electrical connection between all inlet wiresand outlet wires 45 through the coiling and uncoiling of the conductorson the flexible tapes 30 and 31.

FIGS. and 11 illustrate an alternative manner of providing a relativelydisplaceable conductor inside and between the inner drum 1] and theouter tube 13. As shown, the conductor 26 inside the coupler parts isprovided in the form of an accordion-folded strip member, having one end28 fastened to the inner drum l1 and the other end 27 fastened to theouter tube 13. Counterclockwise rotation of the outer tube 13 withrespect to the drum brings the accordion folds of the conductor 26 moreclosely together as shown in FIG. 10, whereas clockwise displacement ofthe outer tube 13 for about one complete revolution opens the folds toalmost fully occupy the slot as best shown in FIG 11. Asin theembodiment of FIG. 1, a series of separated conductors 26 may beprovided and separated by radial slots formed in walls of the inner drum11. A series of such conductors are arranged in alternate arrangement,as previously cable, insulated wire or other. A single unbrokenconductor may be used as shown, or an articulated or otherwise jointedmember may be used. Other forms of extendible winding or windingconfiguration may also be used instead of the coiling as in FIG. 1, theaccordion pleating as in FIG. 10 or the strips or printed circuits ofFIGS. 5 and 6.

What I claim is:

l. A multiconductor rotary electrical coupler comprising:

a pair of rotatably interconnected members,

a plurality of flexible electrical conductors disposed in axiallydisplaced relationship between said members with each conductor havingopposite ends supported with respect to said pair of members each ofsaid flexible electrical conductors having a length greater than thedistance between said members and provided with means for maintainingits axial spacing from the other flexible conductors,

an even number of said flexible electrical conductors with one halfbeing supported to provide a turning torque operating in one direction,and with the other half being oppositely connected between said membersto provide a turning torque operating in the opposite direction,

plural inlet conductors received by one of said members,

with each inlet conductor electrically connected to a different one ofsaid flexible electrical conductors,

plural outlet conductors supported with respect to the other member, andwith each electrically connected to a different flexible electricalconductor.

2. In the coupler of claim 1, said flexible electrical conductorscomprising a plurality of axially spaced conductive strips in loosespiral configuration about one of said members with one end terminaldisposed near the inside of said spiral and the other end terminal nearthe outside of said spiral.

3. In the coupler of claim 1, one of said members comprising a hollowdrum provided with plural radial slots spaced axially along its length,and said other member enclosing said slots, and a flexible electricalconductor disposed in each said slot.

4. In the coupler of claim 3, each of said flexible electricalconductors being in a spiral configuration about the drum and confinedwithin a different slot.

5. In the coupler of claim 3, each of said flexible electricalconductors being disposed in an accordion-pleated configuration andconfined within a different slot.

6. In the coupler of claim 1, each of said electrical conductors beingdisposed in an accordion-pleated expandible configuration between saidpair of members.

7. In the coupler of claim 1, one of said members being hollow toreceive said plural inlet conductors at its interior with each beingelectrically interconnected with a different one of said flexibleelectrical conductors.

8. A rotary electrical coupler comprising:

an inner hollow drum provided with a plurality of radially disposedslots spaced apart axially along its length,

a flexible electrical conductor disposed in spiral configurationprovided in each of said slots and having an inner terminal supported onsaid drum,

an outer hollow tubular member coaxially disposed about said drum andenclosing said slots and conductors and supported in spaced relationtherefrom for relative rotation, an outer terminal of each conductorsupported by said tubular member at a different axial position from theouter terminals of the other conductors,

equal numbers of said electrical conductors being wound clockwise andcounterclockwise to balance turning torques.

9. in the coupler of claim 8, each said flexible conductor comprising anintegral strip spirally wound about said drum and having an innerterminal passing through and retained in a slot in said drum leading tothe interior thereof for access to a separate inlet electricalconductor, and each flexible conductor having an outer terminal passingthrough and retained in a slot in the outer hollow tubular member.

10. In the rotary coupler of claim 1, a plurality of said flexibleelectricalconductors supported in spaced arrangement on a flexibleinsulating tape.

11. in the coupler of claim at least two of said flexible insulatingtapes, each supporting a plurality of said flexible conductors with eachsaid tape supported between said pair of members to oppose the turningtorque of the other tape.

12. A multiconductor rotary coupler comprising: a pair of rotatablyinterconnected coaxially disposed members, at least two elongatedflexible insulating tapes in side-by-side spaced relationship betweensaid members and having their opposite ends supported by said members,each tape having a length greater than the radial distance between saidpair of members permitting limited rotation between said members, eachtape supporting a plurality of spaced apart electrical conductors, saidtapes being oppositely connected between said members whereby theturning torques provided by the tapes are in opposition to one another.

13 In the coupler of claim 12, said tapes being disposed in loose spiralconfiguration between said pair of members, with the spirals in one tapehaving a clockwise direction and the other tape having its spirals incounterclockwise direction.

14. In the coupler of claim 12, a plurality of inlet conductors receivedby one of said pair of members, with a different inlet conductorelectrically connected to each flexible conductor, and plural outletconductors provided on the other member and with each electricallyconnected to a different flexible conductor.

1. A multiconductor rotary electrical coupler comprising: a pair ofrotatably interconnected members, a plurality of flexible electricalconductors disposed in axially displaced relationship between saidmembers with each conductor having opposite ends supported with respectto said pair of members, each of said flexible electrical conductorshaving a length greater than the distance between said members andprovided with means for maintaining its axial spacing from the otherflexible conductors, an even number of said flexible electricalconductors with one half being supported to provide a turning torqueoperating in one direction, and with the other half being oppositelyconnected between said members to provide a turning torque operating inthe opposite direction, plural inlet conductors received by one of saidmembers, with each inlet conductor electrically connected to a differentone of said flexible electrical conductors, plural outlet conductorssupported with respect to the other member, and with each electricallyconnected to a different flexible electrical conductor.
 2. In thecoupler of claim 1, said flexible electrical conductors comprising aplurality of axially spaced conductive strips in loose spiralconfiguration about one of said members with one end terminal disposednear the inside of said spiral and the other end terminal near theoutside of said spiral.
 3. In the coupler of claim 1, one of saidmembers comprising a hollow drum provided with plural radial slotsspaced axially along its length, and said other member enclosing saidslots, and a flexible electrical conductor disposed in each said slot.4. In the coupler of claim 3, each of said flexible electricalconductors being in a spiral configuration about the drum and confinedwithin a different slot.
 5. In the coupler of claim 3, each of saidflexible electrical conductors being disposed in an accordion-pleatedconfiguration and confined within a different slot.
 6. In the coupler ofclaim 1, each of said electrical conductors being disposed in anaccordion-pleated expandible configuration between said pair of members.7. In the coupler of claim 1, one of said members being hollow toreceive said plural inlet conductors at its interior with each beingelectrically interconnected with a different one of said flexibleelectrical conductors.
 8. A rotary electrical coupler comprising: aninner hollow drum provided with a plurality of radially disposed slotsspaced apart axially along its length, a flexible electrical conductordisposed in spiral configuration provided in each of said slots andhaving an inner terminal supported on said drum, an outer hollow tubularmember coaxially disposed about said drum and enclosing said slots andconductors and supported in spaced relation therefrom for relativerotation, an outer terminal of each conductor supported by said tubularmember at a different axial position from the outer terminals of theother conductors, equal numbers of said electrical conductors beingwound clockwise and counterclockwise to balance turning torques.
 9. Inthe coupler of claim 8, each said flexible conductor comprising anintegral strip spirally wound about said drum and having an innerterminal passing through and retained in a slot in said drum leading tothe interior thereof for access to a separate inlet electricalconductor, and each flexible conductor having an outer terminal passingthrough and retained in a slot in the outer hollow tubular member. 10.In the rotary coupler of claim 1, a plurality of said flexibleelectrical conductors supported in spaced arrangement on a flexibleinsulating tape.
 11. In the coupler of claim 10 at least two of saidflexible insulating tapes, each supporting a plurality of said flexibleconductors with each said tape supported between said pair of members tooppose the turning torque of the other tape.
 12. A multiconductor rotarycoupler comprising: a pair of rotatably interconnected coaxiallydisposed members, at least two elongated flexible insulating tapes inside-by-side spaced relationship between said members and having theiropposite ends supported by said members, each tape having a lengthgreater than the radial distance between said pair of members permittinglimited rotation between said members, each tape supporting a pluralityof spaced apart electrical conductors, said tapes being oppositelyconnected between said members whereby the turning torques provided bythe tapes are in opposition to one another.
 13. In the coupler of claim12, said tapes being disposed in loose spiral configuration between saidpair of members, with the spirals in one tape having a clockwisedirection and the other tape having its spirals in counterclockwisedirection.
 14. In the coupler of claim 12, a plurality of inletconductors received by one of said pair of members, with a differentinlet conductor electrically connected to each flexible conductor, andplural outlet conductors provided on the other member and with eachelectrically connected to a different flexible conductor.